OCA1

Oculocutaneous albinism type 1 (OCA1) is a genetic condition caused by biallelic mutations in TYR, the gene encoding the enzyme tyrosinase, which is essential for melanin production in melanocytes. OCA1 is inherited in an autosomal recessive pattern and affects skin, hair, and eyes, resulting in reduced or absent pigment.

There are two main subtypes. OCA1A is characterized by complete absence of tyrosinase activity, leading to white or near-white hair, very light skin from birth, and little to no pigment development over time. OCA1B involves some residual tyrosinase activity, allowing partial pigmentation that may increase modestly with age.

Clinical features include ocular findings such as reduced visual acuity, nystagmus, iris transillumination, and foveal hypoplasia, which contribute to vision impairment. Skin and hair are markedly hypopigmented, and individuals are typically sensitive to sunlight, with a higher risk of sunburn and, later in life, skin cancer.

Diagnosis relies on clinical assessment of pigmentary features and family history, supported by genetic testing that identifies biallelic TYR mutations. Differential diagnosis includes other forms of autosomal recessive albinism caused by mutations in OCA2, TYRP1, SLC45A2, and related genes, as well as other conditions affecting pigmentation and vision.

Management focuses on sun protection and vision support, including sunglasses, corrective lenses or low-vision aids, and regular ophthalmologic and dermatologic monitoring. Genetic counseling is advised for affected families. The prognosis varies with the degree of visual impairment but life expectancy is generally normal. Global prevalence is estimated roughly between 1 in 40,000 and 1 in 100,000, with higher frequency in some populations due to founder mutations.